1. Field of the Invention
This invention relates to an information retrieval system, a method for retrieving information from a data base system, a computer program for carrying out the method and a computer readable medium having the computer program thereon.
2. Discussion of Background Art
The usage of queries to retrieve information from databases is well known in the art. A query is a command, created by the user and conforming to a well defined syntax, that makes a selection from the data available in the database. The item a user wants to retrieve information about is referred to herein as a ‘search subject’. The data on which the query is to be carried out is referred to herein as an ‘information space’. The data that is returned as a response to the query is referred to herein as a ‘result set’. The result set may be used as information space for a next query and so on until the information the user is after has been found. In this way the information space is stepwise reduced, until the goal, which is what the user wants to know about the search subject, of the search has been reached.
Another method of retrieving information, well known in the art, is so called browsing. Browsing relies on a link structure. An example of browsing is a set of HTML pages provided with hyperlinks. The user will start from a start page, choose a link, get a next page, again may choose a link and so on, until he has found the information he is after. Each step moves the user from one location in the information space to another.
In general one can state that a browsing strategy is more suited for an exploratory search, while a querying strategy is more suited for a specific search.
Traditional query systems retrieve results by comparing the terms in a query formulated by the information seeker with terms in individual documents. Only the documents in the corpus that match the terms mentioned in the query are then retrieved. This procedure puts a heavy burden on users to formulate the right query and in the case of a limited amount of domain knowledge, may cause severe cognitive load.
One of the main advantages of querying is that it does not require an intricate link structure. One only has to construct an inverted file, which can be done automatically. This allows a user complete freedom in specifying his query, but at the same time it does not give him any clues about the information contained within the database. Formulating the right query therefore heavily relies on the user's knowledge about the specific domain.
A disadvantage of browsing is that a link structure has to be available. Traditionally, the link structure is created manually, which is quite labour intensive. This seriously hampers the applicability of browsing methods. Above that, while navigating through an information space, a user does not have complete freedom of choice, since only a limited number of links are available. Although this limits the number of possible search paths, it may actually guide a user through the information space.
Also most of the time it is not clear to the user whether the information space at a certain moment in the search process indeed contains the type of information he is looking for. Nowadays available information retrieval systems offer the information seeker too little feedback about that.
It would therefore be beneficial to have available a system that integrates best of both the query and browsing methods so that a user easily can switch between these methods and can optimize his search strategy.